Methods for fabricating display structures

ABSTRACT

An electronic device display may have a color filter layer and a thin film transistor layer. A layer of liquid crystal material may be interposed between the color filter layer and the thin film transistor layer. A layer of polarizer may be laminated onto the surface of the color filter layer. Laser trimming may ensure that the edges of the polarizer are even with the edges of the color filter layer. The thin film transistor layer may have an array of thin film transistors that control pixels of the liquid crystal material in the display. Driver circuitry may be used to control the array. The driver circuitry may be encapsulated in a planarized encapsulant on the thin film transistor layer or may be mounted to the underside of the color filter layer. Conductive structures may connect driver circuitry on the color filter layer to the thin film transistor layer.

This application claims the benefit of provisional patent applicationNo. 61/259,989, filed Nov. 10, 2009, which is hereby incorporated byreference herein in its entirety.

BACKGROUND

This invention relates to electronic devices and, more particularly, todisplay structures for electronic devices such as portable computers.

Portable computers typically have upper and lower housing portions thatare connected by a hinge. The lower housing portion contains componentssuch as printed circuit boards, disk drives, a keyboard, and a battery.The upper housing portion contains a display. When the computer is in anopen configuration, the upper housing portion is vertical and thedisplay is visible to the user of the portable computer. When thecomputer is closed, the upper housing lies flat against the lowerhousing. This protects the display and keyboard and allows the portablecomputer to be transported.

Portable computer displays that are based on liquid crystal displaytechnology include layers of polarizer. The outermost polarizer layer isgenerally formed on the outer surface of a color filter glass layer. Thepolarizer layer often has dimensions that are slightly larger than thecolor filter glass. Use of an oversized polarizer of this type helps toensure that the color filter glass layer is completely covered withpolarizer. However, the overhanging edges of the oversized layer ofpolarizer can give rise to reliability problems when the display is usedin a product. As a result, undersized polarizer layers are sometimesused. With this approach, the size of the polarizer is chosen so as tobe smaller than the dimensions of the color filter glass. Overlappingpolarizer edges are avoided, but a peripheral region on the surface ofthe color filter glass is uncovered. This uncovered region can beunsightly unless hidden from view by a bezel. Use of a large bezel, inturn, may not be aesthetically appealing, particularly in moderndevices.

It would therefore be desirable to be able to produce improved displaysfor electronic devices.

SUMMARY

An electronic device display such as a computer may have a housing. Adisplay may be mounted in the housing. The display may have a colorfilter layer and a thin film transistor layer. A layer of liquid crystalmaterial may be interposed between the color filter layer and the thinfilm transistor layer. A layer of polarizer may be laminated onto thesurface of the color filter layer. Laser trimming may ensure that theedges of the polarizer are even with the edges of the color filterlayer. A shim may be used to help prevent the polarizer layer fromadhering to the color filter layer in certain regions. Using lasertrimming, the edges of the shim may be traced to cut an opening in thepolarizer. The opening may be used to form a camera window for a cameramodule.

The thin film transistor layer may have an array of thin filmtransistors that control pixels of the liquid crystal material in thedisplay. Driver circuitry may be used to control the array. The drivercircuitry may be encapsulated in a planarized encapsulant on the thinfilm transistor layer or may be mounted to the underside of the colorfilter layer. Ink-jet-printed conductive structures may connect drivercircuitry on the color filter layer to the thin film transistor layer. Alayer of black or non-black ink may be interposed between the drivercircuitry and the color filter layer to which the driver circuitry ismounted.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative portable computer withdisplay structures in accordance with an embodiment of the presentinvention.

FIG. 2 is a cross-sectional side view of illustrative display structuresin an electronic device such as a portable computer in accordance withan embodiment of the present invention.

FIGS. 3, 4, 5, and 6 are cross-sectional side views of displaystructures such as a color filter glass layer and thin film transistorglass layer on which driver circuitry has been formed during successivestages of fabrication in accordance with an embodiment of the presentinvention.

FIG. 7 is a cross-sectional side view of display structures in whichdriver circuitry has been mounted on an underside of a color filterglass layer in accordance with an embodiment of the present invention.

FIG. 8 is a top view of a conventional thin film transistor glass layershowing how driver integrated circuits and traces may be formed on thethin film transistor glass layer.

FIG. 9 is a bottom view of a color filter glass layer of the type shownin FIG. 7 showing how underside traces on the color filter glass layermay be used to connect driver integrated circuits to vertical connectionstructures such as ink-jet-printed conductive dots in accordance with anembodiment of the present invention.

FIG. 10A is a top view of a mother glass panel on which structures formultiple displays have been formed in accordance with an embodiment ofthe present invention.

FIG. 10B is a top view of a section of glass that contains multipledisplays that have been cut from the mother glass panel of FIG. 10A inaccordance with an embodiment of the present invention.

FIG. 10C is a top view of display structures for an individual displaythat have been cut from the glass piece of FIG. 10B in accordance withan embodiment of the present invention.

FIG. 10D is a top view of the display structures of FIG. 10C followinglamination of an oversized polarizer layer in accordance with anembodiment of the present invention.

FIG. 10E is a side view of an illustrative laser cutting tool that maybe used to trim excess polarizer material from the edges of the displaystructures after the polarizer material has been attached to the displaystructures as shown in FIG. 10D in accordance with an embodiment of thepresent invention.

FIG. 10F is a cross-sectional view of the display structures taken alongline 103-103 of FIG. 10D prior to laser removal of a circular shim layerin accordance with an embodiment of the present invention.

FIG. 10G is a top view of the display structures after laser edgetrimming and laser shim removal operations have been completed inaccordance with an embodiment of the present invention.

FIG. 11 is a flow chart of illustrative steps involved in formingdisplay structures for an electronic device in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION

An illustrative electronic device such as a portable computer in whichdisplay structures may be provided is shown in FIG. 1. As shown in FIG.1, portable computer 10 may have housing 12. Housing 12, which issometimes referred to as a case, may be formed from one or moreindividual structures. For example, housing 12 may have a mainstructural support member that is formed from a solid block of machinedaluminum or other suitable metal. One or more additional structures maybe connected to the housing 12. These structures may include, forexample, internal frame members, external coverings such as sheets ofmetal, etc. Housing 12 and its associated components may, in general, beformed from any suitable materials such as such as plastic, ceramics,metal, glass, composites, etc. An advantage of forming housing 12 atleast partly from metal is that metal is durable and attractive inappearance. Metals such as aluminum may be anodized to form aninsulating oxide coating.

In general, the components of portable computer 10 can be formed fromany suitable materials. As examples, the components of portable computer10 may be formed from materials such as metals (e.g., aluminum,stainless steel, alloys of metals, electroplated metals, plated andother coated metals, etc.), plastics (e.g., polycarbonate (PC) plastics,acrylonitrile butadiene styrene (ABS) plastics, thermoplastics, PC/ABSplastic blends, etc.), composite materials (e.g., carbon fibers or otherfibers bound by a binder such as a polymer resin), plastics that havebeen injection molded around metal structures, laminated plastic layers,ceramics, metal, glass, composites, metal-filled epoxy, other suitablematerials, and combinations of these and other materials. Components ofportable computer 10 which are described herein as being formed from oneor more specific materials (e.g., housing 12 which is sometimesdescribed herein as being formed from machined aluminum as an example)can be formed from any of the above-mentioned materials, other suitablematerials, or combinations of such materials.

Housing 12 may have an upper portion 26 and a lower portion 28. Lowerportion 28 may be referred to as the base or main unit of computer 10and may contain components such as a hard disk drive, battery, and mainlogic board. Upper portion 26, which is sometimes referred to as acover, lid, or display housing, may rotate relative to lower portion 28about rotational axis 16. Portion 18 of computer 10 may contain a hingeand associated clutch structures and is sometimes referred to as aclutch barrel.

Lower housing portion 28 may have a slot such as slot 22 through whichoptical disks may be loaded into an optical disk drive. Lower housingportion may also have a touchpad such as touchpad 24 and may have keys20. If desired, additional components may be mounted to upper and lowerhousing portions 26 and 28. For example, upper and lower housingportions 26 and 28 may have ports to which cables can be connected(e.g., universal serial bus ports, an Ethernet port, a Firewire port,audio jacks, card slots, etc.). Buttons and other controls may also bemounted to housing 12. Speaker openings such as speaker openings 30 maybe formed in lower housing portion 28 by creating an array of smallopenings (perforations) in the surface of housing 12.

A display such as display 14 may be mounted within upper housing portion26. Display 14 may be, for example, a liquid crystal display (LCD),organic light emitting diode (OLED) display, or plasma display (asexamples). Display 14 may contain a number of layers of material. Thesedisplay structures may include, for example, layers of opticallytransparent materials such as plastic and glass. Layers of plastic andoptical adhesive may also be incorporated into display 14. In a liquidcrystal display, which is sometimes described herein as an example, alayer of liquid crystal material may be formed between a color filterglass layer and a thin film transistor glass layer. The thin filmtransistor glass layer may include an array of thin film transistors.The transistors may drive the image pixels in the display. The colorfilter glass may be used to impart colors to the pixels. Layers ofpolarizer may be formed above and below the color filter glass and thethin film transistor glass. Display structures in display 14 may alsoinclude backlight structures such as a reflective sheet, a light guidepanel, and layers of optical films such as diffuser layers and lightcollimating layers.

Computer 10 may have input-output components such as touch pad 24. Touchpad 24 may include a touch sensitive surface that allows a user ofcomputer 10 to control computer 10 using touch-based commands(gestures). A portion of touchpad 24 may be depressed by the user whenthe user desires to “click” on a displayed item on screen 14.

A cross-sectional side view of a portion of upper housing 26 of device10 (FIG. 1) in which display structures 106 have been mounted. Ingeneral, display structures 106 may be formed from any suitablematerials (e.g., plastic, glass, other optically suitable materials,etc.). Upper housing 26 may, for example, be formed from machinedaluminum. If desired, upper housing 26 may be formed from other suitablematerials such as plastics, composites, etc. Elastomeric gasket 104 maybe used to provide a soft interface between potentially fragile glasslayers in structures 106 and housing 26.

Display structures 106 may produce an image using any suitable displaytechnology (e.g., light-emitting diodes such as an array of organiclight-emitting diodes, liquid crystal display pixels, plasma-basedpixels, etc.). An arrangement in which display structures 106 are basedon liquid crystal display (LCD) technology is sometimes described hereinas an example. The use of LCD structures in display structures 106 is,however, merely illustrative. Display structures 106 may, in general, beformed from any suitable type of display structures. Moreover, use ofdisplays structures 106 in portable computers and other electronicdevices with upper and lower housings is merely illustrative. Displaystructures 106 may be used in a handheld electronic device, atelevision, a tablet computer, a desktop computer monitor, or otherelectronic equipment.

As shown in FIG. 2, display structures 106 may have an upper polarizerlayer 102 and a lower polarizer layer 96. Layers such as layers 102 and96 may be formed from one or more sublayers. For example, layer 102 mayinclude an antireflection coating layer, a stretched plastic layer thatforms the active polarizer portion of layer 102, a polymer compensationlayer, etc. Light guide structures 88 may provide backlight forstructures 106. Light-guide structures 88 may include reflectivestructures such as reflective sheet 90 (e.g., white polyester),light-guide panel 92, and optical films 94. Optical films 94 may includea diffuser layer and light collimating layers (as an example). Ifdesired, light reflection functions may be provided by housing 26.Housing 26 may be formed from a reflective material such as metal and/orthe interior surfaces of housing 26 may be coated with a reflectivecoating such white paint or ink, silver paint or ink, a reflectivematerial such as chromium, etc. In arrangements in which housing 26 ishighly reflective, some or all of reflective sheet 90 may be omitted.

Clearances D2 and D1 help prevent damage to display structure 106 duringuse of device 110. In a typical arrangement, clearance D2 may be about1.2 to 1.8 mm and clearance D1 may be about 0.11 mm. End clearance D3may be about 0.3 mm.

Light from a light-emitting diode array or other backlight source isprovided to an edge of light guide panel 92. Panel 92 and the otherstructures in light guide structures 88 direct this light upwards indirection 108 through thin film transistor layer 98 and color filterlayer 100.

Thin-film transistor substrate glass layer 98 may contain thin-filmtransistors in array 110. Color filter glass layer 100 may contain anarray of optical filters of different colors to provide displaystructures 106 with the ability to display color images. Color filterlayer 100 may be formed from glass into which dye of different colorshas been impregnated, from a glass layer coated with a pattern ofcolored dye, from a glass or plastic layer that is covered with apattern of thin colored filter structures (e.g., filters formed frompolymer or glass containing dye), or any other suitable color filterstructures. A ground plane structure such as ground plane 111 may beformed on the lower surface of color filter layer 100. Ground plane 111may, for example, be formed from a rectangular thin film of indium tinoxide or other transparent conductive material. Liquid crystal layer 112may be controlled by the electric fields produced between the thin-filmtransistors of array 110 and ground plane 111.

Display structures 106 may, if desired, be covered by a layer of coverglass. The cover glass layer adds bulk to device 10, so when size andweight are to be minimized, the cover glass may be omitted as shown inFIG. 2. A cosmetic trim structure such as a bezel may cover the edge ofdisplay structures 106 (e.g., in the vicinity of gasket 104) or, asshown in FIG. 2, the display for device 10 may be implemented without abezel to minimize the thickness of the non-display structures at theedge of housing 26.

Color filter layer 100 may be formed of a durable clear layer (e.g., astrong glass or plastic) that resists damage from contact. Anti-scratchcoatings may also be provided on the surface of color filter layer 100(e.g., as part of polarizer layer 102 or above polarizer layer 102).

To hide the peripheral portions of display structures 106 that lie alongthe outer edges of display housing 26 from view, an opaque material suchas ink layer 114 may be incorporated around the periphery of displaystructures 106 to form a border. Opaque layer 114 may be formed on theunderside of color filter layer 100 or on the upper surface of thin-filmtransistor glass layer 98 (as examples). The opaque material may haveany suitable color (e.g., black, grey, silver, white, blue, red, etc.).

With the arrangement of FIG. 2, color filter layer 100 and thin-filmtransistor layer 98 extend outwardly (in the leftward direction in theorientation of FIG. 2) so as to form an overhanging portion 116 that issupported by the matching ledge in housing 26. If desired, only colorfilter layer 100 may extend in this way (e.g., so that the overhangingportion of layer 100 rests on the ledge formed by housing 26). In thistype of arrangement, the thin-film transistor layer may extend only asfar as light-guide structures 88 of FIG. 2. If desired, portions ofgasket 104 may be interposed between display structures 106 and housing26 in region 116, as illustrated by protruding lower lip portion 105 ofgasket 104 in the example of FIG. 2. Display driver circuitry 118 may,if desired, be formed in region 116 (e.g., as part of thin filmtransistor layer 98 or in a chip mounted on thin film transistor layer98 or color filter layer 100).

As shown in FIG. 2, edge 120 of polarizer layer 102 and edge 122 ofcolor filter layer 100 may be laterally aligned (i.e., these edges maybe placed at the same lateral distance along dimension 126 so that theyare even with each other and are horizontally aligned at vertical axis124). Edge 120 and edge 122 may, for example, be aligned within alateral tolerance of 100 microns or less, 50 microns or less, or 25microns or less. Edge 125 of thin film transistor glass layer 98 mayalso be aligned at axis 124. When polarizer layer 102 is aligned withthe underlying glass layers in this way, the outer surface of display 14has an attractive appearance and potential reliability issues that mightarise in using an oversized polarizer layer may be avoided.

Minimal overlap between polarizer layer 102 and color filter layer 100may be obtained using a trimming operation. With one suitablearrangement, which is sometimes described herein as an example, trimmingoperations may be implemented using a computer-controlled laser trimmingtool.

Polarizer layer 102 may be attached to the planer outer surface of colorfilter layer 100 using any suitable technique. For example, polarizerlayer 102 may be laminated onto the surface of color filter layer 100using pressure sensitive adhesive. A roller or other tool may be used topress the polarizer layer onto the color filter layer with sufficientforce to activate the adhesive.

Driver circuitry 118 of FIG. 2 may be implemented using integratedcircuits. These integrated circuits may be mounted on the upper surfaceof thin film transistor layer 98 or on the underside of color filterglass 100. FIGS. 3, 4, 5, and 6 are cross-sectional side views of someof the display structures of FIG. 2 showing how driver circuits 118 maybe mounted on thin film transistor layer 98 and covered with aplanarized layer of encapsulant.

Initially, no color filter layer may be attached to thin film transistorlayer 98 (FIG. 3).

Following attachment of color filter layer 100 (e.g., using pressuresensitive adhesive) and driver circuits 100, thin film transistor layer98 may appear as shown in FIG. 4. Driver circuits 100 may be formed nearthe edge of thin film transistor layer 98, so as not to obstruct any ofthe main central viewing area of display 14. In a typical arrangement,there may be two or more thin film transistor array driver circuits 118,each of which is located at a different position along the edge of thinfilm transistor layer 98 (i.e., at locations that are further into thepage in the orientation of FIG. 4). Integrated circuits 118 may beconnected to the thin film transistors in thin film transistor layer 98using solder and conductive traces.

After transistor array driver circuitry 118 has been formed on thin filmtransistor layer 98, an encapsulating material such as encapsulant 126may be deposited on top of circuitry 118 and planarized, as shown inFIG. 5. Encapsulating material 126 may be formed from thermally curedepoxy, ultraviolet-light-cured epoxy, other adhesives, plastics,glasses, etc. Planarization operations may be performed by mechanicalpolishing or using a combination of chemical and mechanical polishing(CMP) (as examples). Once planarized, upper planar surface 128 ofencapsulant 126 and upper planar surface 130 of FIG. 5 will typicallylie in the same plane, as shown in FIG. 5. Co-planarity of planarsurface 128 and planar surface 130 may also be obtained by accuratelycontrolling the height and flatness of surface 128 during fabrication(e.g., by using a mold, by controlling the amount of material that isdeposited, etc.).

Following formation of planarized encapsulant 126, polarizer layer 102may be laminated onto the surface of encapsulant 126 and color filterlayer 100, as shown in FIG. 6. Trimming operations may be performed toensure that the edges of polarizer 102 are aligned with the edges ofcolor filter glass 100 (on edges such as the right hand edge in FIG. 6),the edges of encapsulant 126 (i.e., the left edge of FIG. 6). In theconfiguration of FIG. 6, the edges of polarizer layer 102 are alsoaligned with the edges of thin film transistor layer 98.

If desired, thin film transistor array driver circuits 118 may bemounted on the lower surface of color filter layer 100. This type ofarrangement is shown in FIG. 7. As shown in FIG. 7, driver circuit 118may be mounted on a layer of ink such as ink 114. Ink 114 may blockdriver circuit 118 from view in direction 131. Integrated circuit 118may be connected to conductive structure 130 by conductive traces 132.Ground plane 111 may be formed on the lower surface of color filterlayer 100. Ground plane 111 may be, for example, a layer of transparentconductive material such as indium tin oxide. During operation, drivercircuits 118 supply control signals to thin film transistor array 110 onthe surface of thin film transistor substrate 98. Electric fields areproduced between the circuits in array 110 and ground plane 111. Thesefields control the state of individual pixel regions in liquid crystallayer 112.

Ground plane 111 may be grounded using conductive structures such asstructures 128. In conventional liquid crystal displays, structures 128are applied to the lower surface of color filter layers by applyingdrops of liquid using ink jet printing. When the liquid solidifies,conductive vertical structures are formed to short ground plane 111 totransistor array 110.

As shown in FIG. 7, conductive structures 130 may be used tointerconnect circuitry 118 on color filter layer 100 with circuitry 110on thin film transistor layer 98. Conductive structures 130 may beformed using the same type of process that is used to form structures128 or using a different process. Techniques that may be used to formstructures 130 include painting (e.g., applying silver paint with abrush or pad), screen printing, pad printing, using a nozzle or dropperto deposit drops of liquid precursor material such as metal-filledepoxy, sputtering, electrochemical deposition, plating, ink-jet coating,other suitable techniques, and combinations of these techniques. Withone suitable arrangement, which is sometimes described herein as anexample, an ink-jet printer is used to deposit a liquid such asmetal-filled epoxy to form a desired pattern of structures 130 onto theunderside of color filter layer 100. This process may also be used todeposit structures 128.

Once deposited on color filter layer 100, color filter layer 100 andthin film transistor layer 98 may be attached to each other toencapsulate liquid crystal layer 112. When attached in this way, thecircuitry of driver circuits 118 is connected to thin film transistorarray circuitry 110 via traces 132 and structures 130.

In conventional displays, thin film transistor driver integratedcircuits 134 are connected to the thin film transistor array on thinfilm transistor glass 138 using conductive traces 136 on thin filmtransistor glass 138, as shown in FIG. 8.

With an arrangement of the type shown in FIG. 7, traces 132 on thesurface of color filter layer 100 may be used in routing thin filmtransistor array signals from driver integrated circuits 118 to thinfilm transistor array 110. This is illustrated in more detail in the topview of FIG. 9. As shown in FIG. 9, traces 132 may form at least some ofthe routing functions that would conventionally be handled using traces136 of FIG. 8. After passing vertically through conductive structures130, these can be handled using corresponding routing lines in circuitry110 on thin film transistor layer 98 (FIG. 7).

Assembly techniques that may be used for forming display structures suchas the display structures of FIGS. 6 and 7 are illustrated in thediagrams of FIGS. 10A-10G.

In a typical manufacturing process, structures for multiple displays areinitially formed in parallel on a relatively large sheet of “motherglass.” As shown in FIG. 10A, mother glass 142 may contain multiplecopies of color filter glass 100.

Mother glass 142 may be quartered to form smaller panels such as panel144 of FIG. 10B.

As shown in FIG. 10C, a cutting tool such as tool 149 may be used to cutan individual color filter glass layer 100 from panel 144 of FIG. 10B(or, if desired, directly from mother glass 142 of FIG. 10C). Cuttingtool 149 may use a laser, saw, or other computer-controlled cuttingmechanism for cutting color filter glass 100 from panel 144 or glass142. With one suitable arrangement, cutting tool 149 may be implementedusing a multi-head free-shape diamond scriber. A scriber or other suchtool may be used to create cuts with curved sections such as curvedcorners 148 in color filter layer 100 of FIG. 10C.

As shown in FIG. 10C, color filter layer 100 may be provided with afiducial such as fiducial 146. This allows camera-based automaticalignment systems to be used when handling color filter layer 100 duringprocessing. Fiducial 146 may be implemented be forming one or more metalalignment marks on the surface of layer 100 (as an example).

After forming a color filter glass layer of a desired shape, polarizerlayer 102 may be laminated onto the surface of the color filter glasslayer (FIG. 10D). As shown in FIG. 10D, the lateral dimensions ofpolarizer layer 102 may be chosen so as to be slightly larger than thecorresponding lateral dimensions of color filter layer 100 (i.e.,polarizer layer 102 may be oversized relative to color filter layer100). With this type of arrangement, there is a slight overlap(overhang) in the polarizer layer 102 around the peripheral edge portionof the polarizer layer. The polarizer layer may include multiple layersof material (e.g., an antireflection coating layer, an active polarizerlayer, a compensation layer, etc.) or some or all of these layers may beformed during separate lamination steps. Lamination may be performedusing lamination tool 151. With a typical arrangement, lamination tool151 presses downwards on the surface of color filter layer 100 usingrollers. Pressure sensitive adhesive on the underside of polarizationlayer 102 attaches polarization layer 102 to the upper surface of colorfilter layer 100.

Following lamination of oversized polarization layer 102 onto thesurface of color filter glass layer 100, excess polarizer may beremoved. In particular, a trimming tool may be used to cut awayundesired portions of the polarizer layer. The trimming tool may bebased on blade-type cutters, saws, press cutting equipment, or othersuitable trimming equipment. With the illustrative arrangement of FIG.10E, trimming equipment has been implemented using a laser such as laser156. Laser 156 may be a diode laser, a gas laser, a glass laser, acontinuous-wave laser, a pulsed laser, or any other suitable type oflaser. With one suitable arrangement, laser 156 is a carbon dioxidelaser that produces infrared light. Infrared light is absorbed bypolarizer layer 102, which facilitates efficient cutting operations.

The position of laser beam 157 may be controlled using controllablemirrors such as mirror 159 and/or by controlling the position of theworkpiece (i.e., polarizer 102, adhesive 168, and color filter layer100) using translation stages such as translation stage 158. Camera 152may be used to capture images of the workpiece and, using images offiducial 146 (FIG. 10C), may assist in aligning the workpiece relativeto beam 157. Control unit 154 may control laser trimming operations bycontrolling the power of laser 156, by controlling the image acquisitionfunctions of camera 152, by controlling the position of beam 157 (e.g.,by controlling mirror 159 and/or translation stage 158 or otherpositioning equipment), etc. As polarizer 102 is trimmed, excess piecesof polarizer such as piece 102′ of FIG. 10E may be removed from theworkpiece.

Trimming operations may be used to remove pieces of overhangingpolarizer along the edges of color filter glass layer 100 so that theedges of polarizer 102 are accurately aligned with the edges of layer100 (i.e., within a tolerance 100 microns or less, within 50 microns orless, etc.). Trimming operations may also be used to remove portions ofpolarizer 102 elsewhere on color filter layer 100. For example, trimmingoperations may be used to remove a circular piece of polarizer 102 toform a window opening for a camera.

Peripheral pieces of polarizer 102 overhang the edges of color filterlayer 100 and are therefore not attached to any other structures. Duringtrimming, peripheral pieces of polarizer such as piece 102′ of FIG. 10Eare therefore not generally difficult to remove from the workpiece.Unless care is taken, however, the use of adhesive 168 to attachpolarizer 102 to the surface of color filter layer 100 can make itchallenging to remove other trimmed portions of polarizer 102.

One way to facilitate the removal of trimmed pieces of polarizer 102from color filter layer 100 involves the introduction of barrier layermaterial under selected portions of adhesive 168. The barrier layermaterial may be formed from a liquid (e.g., water, solvent, oil, orother substances) or a solid (e.g., plastic, metal, glass, etc.). Inareas where the barrier layer material is present, adhesive 168 isprevented from adhering effectively to the upper surface of color filterlayer 100, thereby facilitating subsequent removal of the portion ofpolarizer that lies above the barrier layer material.

If desired, barrier layer structures may be provided in the form of thinlayers of plastic (“shims”). An example of this type of arrangement isshown in the cross-sectional side view of FIG. 10F. During thelamination process, (FIG. 10D), adhesive 168 may be formed on theunderside of polarizer 102 (e.g., by spray coating, using a roller,etc.). Before laminating polarizer 102 onto the surface of color filterlayer 100, shim 160 (or other suitable barrier layer structure) may beattached to the underside of polarizer 102. Shim 160 may, for example,be placed in contact with adhesive 168 in a location at which it isdesired to form an opening in polarizer 102. After shim 160 has beenplaced on this portion of adhesive 168, lamination tool 151 may laminatepolarizer 102 (and the attached shim) onto the surface of the colorglass layer to form an arrangement of the type shown in FIG. 10F. Lasertrimming equipment of the type shown in FIG. 10E may be used to cutthrough polarizer 102 around the periphery of shim 160 (shown as edgelocations 162 in FIG. 10F). To avoid damaging shim 160, laser light maybe focused adjacent to—but just beyond—the outer edges of shim 106during trimming.

After the laser cut along the edge of shim 160 has been made, portion164 of polarizer 102 will be attached only to shim 160 and not to theremaining polarizer on color filter layer 100. Portions 166 of polarizer102 are attached to color filter layer 100 by adhesive 168, so portions166 will remain in place following trimming. Shim 160 is not attached tocolor filter layer 100 by adhesive, so shim 160 and portion 164 may beremoved from the workpiece. The shape of shim 160 and the shape of thecorresponding laser cut in polarizer 102 that is used to liberate shim160 and portion 164 may be circular, rectangular, etc. FIG. 10G is aview of the upper surface of color filter layer 100 after a circularshim 160 has been removed from color filter layer 100 to form circularcamera hole 150. Once color filter layer 100 has been assembled to forma complete display, a camera module may be mounted behind hole 150.

In arrangements in which a layer of ink is formed around the peripheryof the color filter layer to block components from view, the portion ofthe ink layer that lies behind the hole may be omitted to ensure thatthe camera module will not be blocked by ink. Because no polarizer 102is present in the opening, camera operation is not adversely affected bythe presence of polarizer.

Although formation of a single opening is illustrated in FIGS. 10A-10G,any suitable number of polarizer openings may be formed if desired.Moreover, additional layers of films may be laminated and trimmed in thesame way. For example, an antireflection coating layer may be laminatedonto the surface of polarizer 102 (e.g., in a situation in whichpolarizer layer 102 does not already contain an antireflection coatinglayer).

Illustrative steps involved in forming display structures for device 10are shown in FIG. 11.

At step 170, display structures (e.g., color filters) may be fabricatedas part of mother glass 142 of FIG. 10A.

After forming the color filter mother glass, the mother glass mayoptionally be divided into smaller panels (e.g., mother glass 142 may bequartered to form panels such as panel 144 of FIG. 10B).

At step 172, cutting tool 149 (e.g., a diamond scribing tool) may beused to cut an individual piece of color filter glass from mother glass142 or panel 144 (i.e., layer 100 of FIG. 10C).

At step 176, adhesive barrier structures such as shim 160 may beattached to the underside of adhesive layer 168 and associated polarizerlayer 102 and the resulting masked polarizer layer may be laminated ontothe upper surface of color filter layer 100 using lamination tool 151.

At step 178, laser trimming equipment of the type described inconnection with FIG. 10E or other suitable cutting equipment may be usedto remove the overlapping edges of polarizer 102 and may be used to cutout shim 160 to form opening 150. Because laser trimming is used to trimaway excess edge portions of polarizer 102, the edges of polarizer 102may be accurately aligned with the edges of color filter glass 100.Following trimming operations to remove the peripheral edge portions ofthe oversized polarizer layer, the edges of the polarizer will be evenwith the edges of the color filter glass layer. Because of the use ofshim 160 or other such adhesive barrier materials, adhesive 168 isprevented from adhering to areas of color filter layer 100 wherepolarizer openings are desired.

As illustrated by step 180, some or all of the operations of steps 170,172, 174, 176, and 178 may be repeated as desired (e.g., to addadditional layers of material such as antireflection coating layers thathave edges that are aligned with the edges of color filter glass 100).If desired, planarization operations may be performed to help ensurethat the top surface of each layer is planar before subsequent layersare laminated. For example, if a circular hole has been formed in thepolarizer layer and it is desired to deposit a separate antireflectionlayer, a liquid such as ultraviolet curable epoxy or other planarizingsubstance may be deposited into the circular hole. This planarizingsubstance can be used to fill the circular hole (i.e., by filling thehole sufficiently that the upper surface of the epoxy fill is verticallyaligned and therefore co-planar with the planar outer surface of thepolarizer). After planarizing in this way, the surface of the polarizerwill be smooth and even, thereby facilitating the attachment ofsubsequent layers (e.g., the antireflection coating).

Approaches of the type shown in FIG. 11 may be used in forming displaystructures of the type shown in FIG. 6 or FIG. 7 (as examples). Forexample, a structure of the type shown in FIG. 5 may be formed beforepolarizer layer 102 is laminated onto the color filter by attaching thinfilm transistor layer 98 to the rear surface of the color filter,mounting driver circuits 118, and forming planarized encapsulantstructure 126 over circuits 118. Structures of the type shown in FIG. 7without polarizer layer 102 may also be formed before polarizer layer102 is laminated onto the color filter at step 176. If desired, some ofthese fabrication steps (e.g., the attachment of thin film transistorlayer 98 to color filter layer 100) may take place after the polarizerlamination and trimming operations of FIG. 11 have been performed.

The foregoing is merely illustrative of the principles of this inventionand various modifications can be made by those skilled in the artwithout departing from the scope and spirit of the invention.

What is claimed is:
 1. A method for forming display structures,comprising: forming a color filter layer; laminating an oversizedpolarizer layer onto the color filter layer, wherein edges of theoversized polarizer layer extend laterally past edges of the colorfilter layer; cutting an opening in the polarizer layer, wherein cuttingthe opening comprises cutting out a shim that is interposed between thepolarizer layer and the color filter layer; and trimming off peripheralportions of the oversized polarizer layer that has been laminated ontothe color filter layer so that the edges of the polarizer layer aftertrimming are even with the edges of the color filter layer.
 2. Themethod defined in claim 1 wherein trimming off the peripheral portionsof the oversized polarizer layer comprises performing laser trimmingoperations with laser trimming equipment.
 3. The method defined in claim1 wherein cutting the opening comprises cutting a camera window in thepolarizer layer.
 4. A method for forming display structures, comprising:forming a color filter layer; laminating an oversized polarizer layeronto the color filter layer, wherein edges of the oversized polarizerlayer extend laterally past edges of the color filter layer and whereinlaminating the oversized polarizer layer onto the color filter layercomprises attaching the polarizer layer to the color filter layer usingadhesive; interposing an adhesive barrier material between the adhesiveand the color filter layer in a given region of the color filter layer;and trimming off peripheral portions of the oversized polarizer layerthat has been laminated onto the color filter layer so that the edges ofthe polarizer layer after trimming are even with the edges of the colorfilter layer.
 5. The method defined in claim 4 wherein the given regionis a circular camera window region.
 6. The method defined in claim 4wherein the adhesive barrier material comprises a plastic shim.
 7. Themethod defined in claim 6 further comprising cutting out the plasticshim after laminating the polarizer layer onto the color filter layer.8. The method defined in claim 7 wherein the plastic shim has peripheraledges and wherein cutting out the plastic shim comprises using a laserto cut through the polarizer along the peripheral edges of the shim. 9.The method defined in claim 7 further comprising: mounting a thin filmtransistor array driver integrated circuit onto a thin film transistorglass layer; encapsulating the integrated circuit in an encapsulant; andattaching the thin film transistor glass layer to the color filterlayer, wherein the thin film transistor glass layer comprises an arrayof thin film transistors that control pixels in a display formed usingthe color filter layer.
 10. The method defined in claim 9 wherein thethin film transistor glass layer comprises a planar surface, the methodfurther comprising polishing the encapsulant to form a planar surface onthe encapsulant that is vertically aligned with the planar surface ofthe thin film transistor glass layer before attaching the thin filmtransistor glass layer to the color filter layer.
 11. A method forforming display structures, comprising: forming a color filter layer;mounting a thin film transistor array driver integrated circuit onto thecolor filter layer such that the thin film transistor array driverintegrated circuit at least partially overlaps the color filter layer;laminating an oversized polarizer layer onto the color filter layer,wherein edges of the oversized polarizer layer extend laterally pastedges of the color filter layer; and trimming off peripheral portions ofthe oversized polarizer layer that has been laminated onto the colorfilter layer so that the edges of the polarizer layer after trimming areeven with the edges of the color filter layer.
 12. The method defined inclaim 11 further comprising: forming conductive structures thatelectrically couple the thin film transistor array driver integratedcircuit with an array of thin film transistors on a thin film transistorglass layer.
 13. The method defined in claim 12 wherein forming theconductive structures comprises ink-jet printing conductive dots. 14.The method defined in claim 13 further comprising ink-jet printingadditional conductive dots that electrically connect an indium tin oxideground plane on the color filter layer with circuitry on the thin filmtransistor glass layer.
 15. Display structures, comprising: a colorfilter glass layer; a thin film transistor glass layer; thin filmtransistor driver integrated circuits attached to the color filter glasslayer; traces on the color filter glass layer that are interconnectedwith the thin film transistor driver integrated circuits; an array ofthin film transistors on the thin film transistor glass layer; andconductive dots that interconnect the traces on the color filter glasslayer with the array of thin film transistor on the thin film transistorglass layer.
 16. The display structures defined in claim 15 wherein theconductive dots comprise ink-jet dots.
 17. The display structuresdefined in claim 16, wherein the color filter glass layer has an outersurface and edges, the display structures further comprising: a liquidcrystal layer between the color filter glass layer and the thin filmtransistor glass layer; and a polarizer layer on the outer surface ofthe color filter glass layer, wherein the polarizer layer has edges thatare even with the edges of the color filter glass layer within atolerance of less than 100 microns.
 18. The display structures definedin claim 17 wherein the edges of the polarizer layer compriselaser-trimmed polarizer edges.
 19. The display structures defined inclaim 17 further comprising a layer of ink interposed between the thinfilm transistor driver integrated circuits and the color filter glasslayer, wherein the ink has a non-black color.
 20. An electronic device,comprising: a housing; a display mounted in the housing, wherein thedisplay comprises a polarizer having edges and a color filter layerhaving edges that are laterally aligned with the edges of the polarizerwherein at least one integrated circuit is mounted to the color filterlayer such that the at least one integrated circuit at least partiallyoverlaps the color filter layer.
 21. The electronic device defined inclaim 20 further comprising a gasket that is interposed between thehousing and the color filter layer, wherein the edges of the polarizerare not covered by a bezel.
 22. The electronic device defined in claim20 further comprising a layer of ink interposed between the integratedcircuit and the color filter layer at least in peripheral portions ofthe color filter layer, wherein the ink has a color other than black.23. The electronic device defined in claim 20 wherein the displaycomprises: a thin film transistor glass layer having transistorcircuitry; a layer of liquid crystal material interposed between thethin film transistor glass layer and the color filter layer; andconductive structures that electrically connect the integrated circuitto the transistor circuitry of the thin film transistor glass layer. 24.The electronic device defined in claim 23 wherein the conductivestructures comprise ink-jet dots.
 25. The electronic device defined inclaim 20 wherein the edges of the color filter layer are laterallyaligned with the edges of the polarizer to within a tolerance of 100microns.
 26. The electronic device defined in claim 20 wherein thedisplay comprises: a thin film transistor glass layer having transistorcircuitry; a layer of liquid crystal material interposed between thethin film transistor glass layer and the color filter layer; a thin filmtransistor array driver integrated circuit mounted to the thin filmtransistor glass layer and electrically connected to the transistorcircuitry; and encapsulant over the thin film transistor array driverintegrated circuit.
 27. The electronic device defined in claim 26wherein the encapsulant has a planar surface and wherein the thin filmtransistor glass layer has a surface that lies in a common plane withthe planar surface.